Communication between electronic control devices as well as control and monitoring of sensors and actuators in motor vehicles are now increasingly being handled by bus systems, an example of which is the controller area network (CAN) bus. In these systems, electrical signals are transmitted via electrical lines between a sending and a receiving bus station. During operation, such lines are susceptible to damage due to mechanical load or other influences, leading to transmission faults. Damaged lines should no longer be used in a bus system, but conventional systems have only limited ability to detect faults on the lines of a bus system. Thus, the options for reacting to a detected fault are limited, for example, to disconnecting the damaged section. Furthermore, conventional mechanisms for testing bus lines are limited to measuring the voltage of the bus lines. This has the disadvantage that bus lines, which tend to oscillate because of a particular line length, cannot be monitored reliably for faults. Examples of such faults are short circuits to external voltages (such as the supply voltage) or short circuits to ground.